introduction of waves

2. CARRIERS OF ENERGY

4. What’s the underlying theme?

6. What is a wave?
WAVE - a vibration or
disturbance in space.

8. What is a wave?
• Waves transfer energy
without transferring matter.

11. How are waves classified?
Waves are classified by WHAT they
move through or by HOW particles
move through them.

13. What material do waves move through?
MEDIUM- the substance that waves
travel through and need to have in
order to move.

15. Types of Progressive Waves
According to how particles move through them
• Transverse waves
• Longitudinal Waves

17. Transverse Waves
Particles move
perpendicular to
the motion of the
wave

19. Wavelength
Crest
Amplitude
Trough

21. Longitudinal Waves
particles move
parallel to the
motion of the wave.

23. Longitudinal Waves
Compression- a crowded
area causing a high
pressure region
Rarefaction- a spread
out area causing a low
pressure region

25. Wave Characteristics

26. What is the frequency of Radio 4 long wave
that broadcasts at a wavelength of 1500 m?
• c = fλ
 We want the frequency so we must
rearrange:
f = c/λ
 f = 3 × 108 m/s ÷ 1500 m = 200 000 Hz =
200 kHz

28. Wavelength (λ)
The distance from crest to crest
(or trough to trough); expressed
in meters

29. WAVELENGTH

31. Wave Characteristics
Wave velocity (v)
Distance travelled by a wave
crest in one period.
Unit: m/s
v= λ/T

32. Wave Characteristics
Period (T)
The time it takes a wave to travel a
distance equal to a wavelength;
Unit: seconds
T= 1/f

35. Amplitude (A)
The distance of crest (or trough)
from the midpoint of the wave

37. Wave Characteristics
Frequency (f)
The number of waves that
passed a fixed point per second
Unit: hertz (Hz)
f= 1/T

41. Types of Waves
According to what they move through
(Medium)
• Electromagnetic waves
• Mechanical Waves
• Matter Waves

42. Electromagnetic Waves
Waves that can travel through matter or
empty space where matter is not present.

44. Types of Electromagnetic
Waves
• radio waves
• microwaves
• infrared waves
• visible light
• ultraviolet rays
• X-rays
• Gamma ray

47. Mechanical Waves
• Needs a medium
• require the particles of the medium to vibrate in
order for energy to be transferred.

49. Types of Mechanical
Waves
• water waves
• earthquake/seismic waves
• sound waves
• waves that travel down a
rope or spring

50. The Wave Equation
There are three measured
quantities in electromagnetic
waves:
The speed;
The wavelength;
The frequency.

51. wave speed (m/s) = frequency (Hz) ×
wavelength (m)
v = f × λ
The strange looking symbol that looks like an upside-
down "y" is lambda, a Greek letter "l". It is the physics
code for wavelength. The other codes are:
c - wave speed (for electromagnetic waves c = 3 × 108
m/s)
f - frequency.

52. Wave Velocity
𝑣 =
𝐹
𝜇
𝑜𝑟 𝑣 =
𝐹𝐿
𝑚

53. DEFINING WAVELENGTH

54. The Transverse Wave

55. Longitudinal Waves

56. TRANSVERSE &
LONGITUDINAL WAVES

59. Reflection
When a wave hits a
surface through
which it cannot pass,
it bounces back.

60. Reflection
• Reflection does
not change the
speed or frequency
of the wave, BUT
the wave can be
flipped upside
down!

61. Refraction
The bending of a wave as it
enters a new medium.
• It is caused by a change in
the speed of the wave as
it moves from one
medium to another
• Greater change in speed =
more bending of the wave